The present invention relates to a sounder control system.
Sirens employed in vehicle alarm systems include piezoelectric sounders or speakers which are powered by a voltage supply from the vehicle battery. In the event that supply from the vehicle battery fails or is disconnected, a backup battery is provided to ensure the siren can still be activated. Most vehicle alarm systems are configured, for example, to activate the siren if the vehicle battery is disconnected when the alarm system is armed. The backup battery however is normally only able to provide about a 6-9V supply to the siren, instead of the normal 12V supply provided by the vehicle""s battery, and this gives rise to a significant drop in the performance of and sound pressure level generated by the siren. The other difficulty encountered with existing vehicle sirens is that the sound pressure level generated varies considerably across the frequency range for which the siren is to be activated, primarily because of a sounder""s resonance behaviour. It is desirable to be able to provide a vehicle siren which generates a predetermined sound pressure level regardless of supply voltage, signal frequency, temperature or component tolerances.
In accordance with the present invention there is provided a sounder control system, including a converter circuit for converting a drive signal to a signal for activating a sounder and a drive circuit for generating said drive signal. The drive circuit includes a microprocessor for receiving at least one input signal representative of one of a plurality of control parameters for the sounder control system and for adjusting the drive signal on the basis of the at least one input signal, such that said sounder exhibits a predetermined sound pressure level characteristic.
The present invention also provides a sounder control system, including a converter circuit for converting a drive signal to a signal for activating a sounder and a drive circuit for generating the drive signal. The drive circuit includes a microprocessor for receiving a voltage signal representative of the level of a supply voltage for the sounder control system and for adjusting the drive signal on the basis of the voltage signal, such that the sounder exhibits a predetermined sound pressure level characteristic.
The present invention further provides a sounder control system, including a converter circuit for converting a drive signal to a signal for activating a sounder and a drive circuit for generating said drive signal. The drive circuit includes a microprocessor for receiving a temperature signal representative of the temperature inside a housing of the system and the sounder and for adjusting the drive signal on the basis of the temperature signal, such that the sounder exhibits a predetermined sound pressure level characteristic.
The present invention also provides a siren control system that includes a transformer with a secondary coil connected across a sounder and a primary coil, a switch connected to said primary coil to cause current to flow in the primary coil when activated, and a control device for controlling activation of the switch such that said sounder exhibits a predetermined sound pressure level characteristic.